Sensor assemblies have been used to measure properties of fluids, such as fluid flow, density, viscosity, conductivity, temperature, among others. Moreover, through the measurement of multiple properties of a fluid, accuracy can be improved.
For example, U.S. Pat. No. 8,326,555, which incorporated by reference, disclosures a system and related method measuring conductivity/resistivity of water having high purity, using both a temperature sensor and a conductivity/resistivity sensor. The system calibrates the sensor continually during use, in real time, resulting in highly improved accuracy. More particularly, the system determines change in resistivity over a change in temperature (a collected R/T slope) from the collected temperature measurements and the collected resistivity measurements. The system compares the collected R/T slope to a standardized R/T slope at a temperature value corresponding to a midpoint temperature of the temperature measurements over the prescribed time interval. Based on the comparing, the system provides a compensated measurement for resistivity or conductivity of the water source. As a result, the system can calibrate the sensor continually during use, in real time, resulting in improved accuracy of the water purity measurement.
Such combined measurement strategies rely upon timely and accurate measurements. Although current sensors for temperature and conductivity have been generally effective for the above system, shortfall exists. For example, the time delay between conductivity and temperature measurements can make the correlation to determine the water purity inaccurate or impossible when the process changes too quickly. Furthermore, classical temperature sensors can have limited resolution and frequently suffer from comparably high signal noise.
It should therefore be appreciated that there remains a need for a sensor assembly that addresses these concerns. The present invention fulfills these needs and others.